Marine propeller



Patented Aug. 2.6, 1952 UNITED STATES PATENT OFFICE MARINE PROPELLER uBert o. Godfrey, Brooklyn, N. Y. Application september 29, 1951, serialNo. 248,911

1 There is a type of marine propeller which is especially designed foruse with an auxiliary inboard engine of a sail boat. In order to lessenthe drag of the propeller during sailing, the blades of such propellersare arranged to fold automatically into a trailing position with respectto the hub, this action occurring primarily as a result of the relativeaftward movement of the water past the blades during nonpowered forwardmovement of the craft. Whenever it is desired to apply power throughsuch a folded propeller, rotation of the shaft and the propeller hubwill start the blades outwardly by the action of centrifugal force uponthe blades, whereupon continuance of the rotation will develop a slightthrust forwardly by the reaction of the blades aftwardly against thewater, and this will urge the blades fully'outwardly against stops intoa normal outflung position of use, wherein they will remain as long assuch rotation and forward propulsive thrust continues. Whenever rotationof the propeller ceases, the blades will fold down under the influenceof the relative aftward movement of thewater past the blades, as theboat glides forwardly.

' It becomes evident that there would'be no such relative aftwardmovement of water past the blades if it were attempted to reverse thepropeller to back the boat from a standing start, for instance, awayfrom a dock. To my knowledge ,the only way that such propellers caneffect powered aftward movement is to rotate the propeller at asufliciently high speed that the centrifugal effect on the blades willhold them somewhat outwardly and produce some--even if a veryslight-aftward thru-st on the craft, as compared to the normal forwardpropulsive thrust. This is a very unsatisfactory and wasteful way bywhich the objective can but lamely be accomplished.

V It is the primary object of the present invention to provide means foruse with such propellers which will lock the blades in outung position,and hold them there, even after cessation of rotation of the propeller,for a brief period of time, so that during that period the sense ofrotation can be reversed, and when reversed-the blades remaining lockedin positionwill develop full aftward thrust. However, since theunlocking is retarded during but a brief period of time, to

all practical intents and purposes the blades will fold down intotrailing position of disuse automatically following either aftward orforward powered movement, as soon as nonpowered forward movementreoccurs. l y

7 claims. (o1. 17o-160.12)

Thegeneral object of this invention has already been indicated. It is afurther object to provide mechanism of this nature which shall becompact, inexpensive, simple in construction and in action, andreliable, operating wholly automatically and without more than passingattention on the part of the'pilot. -It is also an object to provide inl such mechanism simple means for retarding initial disengagement ofthe' locking elements, yet devices to this end of such nature as willnot appreciably retard eventual disengagement, nor effective engagementof thelocking elements yat any time. I

My invention comprises a novel propeller and a novel automatic lockingand unlocking arrangement employed in conjunction'with the parts of thepropeller, all as shown in the accompanying drawings, and as will bedescribed and claimed hereinafter.

Figure 1 is a view in the axial direction, with the hub transversely insection.

Figure 2 is in part a section, and in part an elevation of the hub.

Figure 3 is an enlarged sectional detail of the locking elements and themeans to retard their disengagement initially.

On the propeller shaft l is mounted the recessed hub 2, in any suitablemanner, its form and manner of mounting beingimmaterial. The propellerillustrated is shown as having two blades 3,r` each of which is formedwith a flat root portion iipwhich is pivotally mounted at '5, upon anaxis arranged chordwise within the hub 2. Each such blade may swing intoa trailing position of disuse about the pivot at 5, or by water reactionwhen rotated may be urged outwardly against a xed stop 6 into itsoutflung position of use.

The arrangements so far described are known, but it is'not essentialthat these particular forms and arrangements be employed, and they are'chosen merely as typical.

Each 'blade root 4 is provided with a locking element, such as therecess 1, and a complemental locking element is carried by the hub, suchas the locking pin 8 mounted in a bore in the hub which parallels thepivot means at 5. These locking pins 8 are shftable in the direction oftheir length, and each is so located that when the corresponding blade 3is in its outflung position, the locking pin 8 may engage within thelocking recess l `of that blade.

Such movement of the locking pin 8 is accomplished under the influenceof a centrifugal mass 9 pivoted at I0 within a recess of the hub, andhaving a finger Il which engages within a notch l2 of the locking pin 8,to shift the latter. The arrangement is such that when the centrifugalmass is retracted in its inward position, shown in dash lines in Figurel, the locking pin is withdrawn from locking engagement, whereas whenthe centrifugal mass 9 is centrifugally thrown outwardly to the fullextent, the locking pin will have been moved into locking engagement, asit is shown in full lines in the same figure.

It is preferred that resilient means such as a spring I3 be employed, soarranged as to urge the centrifugal mass into its inward position, andconsequently acting also to urge the locking pin 8 into its disengagedposition. The locking means are thereby urged always, except when underthe influence of centrifugal force acting on the masses 9, into unlockedposition, leaving the blades 3 free to move to their trailing position.If the blades are in their trailing position, the springs will not be ofsufficient strength to pree vent the blades moving into their outflungpositions of use, when acted on by centrifugal force and by waterreaction.

In order to insure that the locking elements will not disengageimmediately upon cessation of the rotation of the hub, time-delay meansare employed. There are various ways of accomplishing this result, manyof which would be suitable, and as an example of such an arrangement theexterior end of each bore, in which a locking pin is shiftable is closedby a plug I4. to provide a closed, liquid-lled space I5 variable involume as the locking pin shifts therein. Admission thereto is throughthe angled passage I6 in this end of the locking pin 8 and a passage l1in the hub. The relative positions of the registering portions of thepassage I6 and the port l1 are such that there is no appreciablerestriction until the locking pin approaches the end of its lockingmovement, and after it has already engaged within the locking recess l.As it approaches the end of this movement, there is a restriction whichslows down the movement. correspondingly reverse or unlocking movementof the locking pin 8 is similarly retarded by the small size of theorifice between the passage i6 and port Il, but under the urging of thespringf|3 the locking pin continues to withdraw, and after a brief ormomentary retardation the locking pin moves freely again to its;unlocked position.

In operation, the blades being unlocked, will swing downwardly abouttheir pivots at 5 into the trailing position of disuse as shown inFigure 2 in dash lines, purely by the relative water movementaccompanying forward nonpowered movement of the boat. Whenever poweredforward propulsion is desired, rotation of the shaft l and hub 2 startsthe blades outwardly by centrifugal action and the water reactioncompletes their outward movement. At the same time the centrifugal forceurges the masses 9 outwardly about their pivots at I0, and the lockingpins 8 will engage each within its locking recess 1, to lock the bladesin their outung position.v This is not necessary during powered forwardpropulsion, nor is it objectionable. If, however, it is desired ltoreverse the propulsive effect, rotation of the hub 2 must cease, atleast Ymomentarily, as it goes throughthe reversal. Were it not for thelocking elements and the delay in disengaging them, this reversal wouldmerely act to permit collapse of theblades intor their position ofdisuse. Since, however, the locking elements are still engaged, and donot disengage immediately uponV cessation of rotation, but only after amomentary pause, it follows that if the pilot will only be prompt inreversing the sense of rotation, the locking elements will be retainedin their locked position of engagement, and consequently will enablepowered `reverse propulsion of the boat. Immediately reverse rotationcommences, the masses 9- are thrown centrifugally outwardly again andthe locking elements again come into full engagement, which continues aslong as there is rotation of the hub, regardless of the sense of thatrotation.

If it is desired to propel the boat aftwardly from a standing start, aswhen backing away from a pier, or after disengagement of the lockingelements has permitted the blades to swing aftwardly, it is onlynecessary to start the propeller shaft forwardly briefly andmomentarily, in order to fling the blades outwardly again and to lockthem thus outfiung, and then before there has been any appreciableforward propulsion, to reverse the shaft. It will be found that theblades have become locked in outflung position and will again give fullrearward propulsive effect. The momentary forward rotation will havelittle effect on the boat, for it is so promptly propelled aftwardly.

Since the retention of the blades in outilung position is for only abrief moment following cessation of rotation, they will never remainlocked in outlung position while there is any appreciable forward waymaintained by the boat, nor long after rotation of the propeller shaftand hub ceases.

I claim as my invention:

l. In a marine propeller which includes a hub and blades mounted thereonfor movement between a trailing position of disuse and an outwardlyflung propulsive position of use, and urged into such position of use,at least in part, by the water reaction forces on the bl-ades such asaccompany forward propulsive rotation, means on the hub and meansmovable with the blade and positioned to register with said first meansand to interengage with the latter when the blade is outfiung, meansautomatically operable under the influence of the hubs rotation to urgesaid two interengageable means into engagement, and likewise under theinfluence of cessation of rota.- tion to urge them out of engagement,and means operable automatically at cessation of rotation to retardmomentarily the initiation of their disengagement.

2i In a marine propeller which includes a hub and blades pivotallymounted thereon, on chordal axes, to' fold into trailing positions ofdisuse, or to swing outwardly upon such axes against stops into outiiungwater-'reactive positions of use when the propeller is rotated forforward propulsion, meansyto lock said blades in such outl'iung positi:is preparatory to reverse rotation, said locking means' including alocking element carried by eaclr blade, and a complemental lockingelement shiftably mounted in the hub, in positions for inter-engagementwhen the blades are in their outun'g positions, and a mass mounted onthe hub for shifting under the influence of centrifugal forceaccompanying rotation of the hub, and operati'vely connected to saidhub-mounted locking element tov shift the" latter into engagement with:e blade-carried locking element, as a result of suclhrotation.

3. A marine propeller as inY claim 2, including resilient means urgingvsaid centrifugal mass radially inwardly andv its hub-mounted lockingelement towards unlocked position, and means to retard such movementsmomentarily following cessation of the hubs rotation.

4. A marine propeller as in claim 2, wherein the hub-mounted lockingelement is formed as a pin received within a bore in the hub whichparallels and is located a given radial distance from the chordalpivotal mount of the blade, and the complemental blade-carried lockingelement is formed as a recess in the blades root at the same radialdistance, and at a location to register with said pin when the blade isoutung.

5. A marine propeller as in claim 4, including an orifice located tocooperate with the pin, as the latter is shifted, and to be constrictedby the pin during initiation of unlocking movement, to retard suchunlocking movement momentarily.

6. In a marine propeller, in combination with a hub and with bladesmounted and guided on said hub for relative movement between an outungoperative position and a trailing position of disuse, and for movementinto such outung position in part by centrifugal force and in part bywater reaction accompanying forward propulsive thrust, and movable intosuch trailing position by relative aftward water movement accompanyingnonpowered forward movement, a centrifugal mass mounted in the hub, alocking pin shiftably mounted in the hub adjacent and movable towardsand from each blade, a complemental locking recess in each blade,located for engagement by the corresponding locking pin when its bladereaches outfiung position, an operative connection between saidcentrifugal mass and said pin, arranged to urge the pin into lockingengagement withinits locking recess, whenever rotation of the hubimposes a centrifugal force on BERT O. GODFREY.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 731,020 Char-les June 16, 19032,198,475 Dorner Apr. 23, 1940 2,532,371 Petersen Dec. 5, 1950

